目的：探索中国人尿路上皮癌（urothelial carcinoma, UC）中成纤维细胞生长因子受体（fibroblast growth factor receptor, FGFR）家族（FGFR1~4）基因变异谱及人类表皮生长因子受体2（human epidermal growth factor receptor 2, HER2）蛋白表达和基因状态，为划分适于不同靶向治疗方案的潜在获益人群及开发新的治疗策略提供遗传学依据。 

方法：收集2022年1月至8月期间存档于北京协和医院经福尔马林固定石蜡包埋（formalin-fixed paraffin-embedded, FFPE）的UC手术标本133例，通过新一代测序（next-generation sequencing, NGS）识别FGFR基因变异。同时，采用免疫组织化学（immunohistochemistry, IHC）方法检测HER2蛋白表达，随后对HER2 IHC2+的标本以荧光原位杂交（fluorescence in situ hybridization, FISH）方法进一步评估其HER2基因状态。分析UC患者HER2和/或FGFR变异与临床病理特征的关系。

结果：在133例UC中，检出50例FGFR基因变异（37.6%）。变异类型复杂多样，包括突变、融合、两种突变共存、突变和融合共存，以及与其他FGFR家族基因变异共存。最常见是FGFR3变异，占总体人群的27.8%（37/133），其中包括31例FGFR3突变、2例FGFR3突变/FGFR3融合共存、2例FGFR2/FGFR3共突变及2例FGFR3/FGFR4共突变。发现FGFR2基因突变4例（3.0%，4/133）、FGFR4突变1例（1/133）及FGFR2/FGFR4共突变1例。本队列中FGFR双变异共存者占20.0%（10/50）。未发现FGFR1变异。我们检出的8种突变（G548R、 G370C、M528I、R30C、A790T、S371C、S22L和K650T）及4种融合（CASP7::FGFR2、FGFR2::BICD2、FBLN2::FGFR2和FGFR3::GRSF1）不在FGFR靶向药Erdafitinib伴随诊断覆盖范围内。FGFR变异与HER2过表达（IHC 2+或3+）共存的病例共31例（62.0%，31/50）。

FGFR变异与肿瘤分级、浸润程度和Ki-67指数负相关。HER2表达水平与肿瘤部位相关，与肿瘤分级和Ki-67指数正相关。FGFR与HER2双异常与肿瘤分级、浸润程度及Ki-67指数负相关。

结论：UC中存在FGFR2/3/4基因变异；FGFR阳性UC高度富集HER2过表达。FGFR和HER2双抑制可能是有效治疗UC的候选策略。有必要扩大样本量验证本发现并开展相关的临床研究。

Objective: To explore the gene expression and gene status of fibroblast growth factor receptor(FGFR) family (FGFR1-4) and human epidermal growth factor receptor 2(HER2) in urothelial carcinoma(UC) in China, and to provide a genetic basis for the potential benefit of different targeted therapies and the development of new therapeutic strategies.

Methods: A total of 133 formalin-fixed paraffin-embedded(FFPE) UC surgical specimens archived at Peking Union Medical College(PUMC) Hospital between January and August 2022 were collected, and the FGFR gene was identified by next-generation sequencing(NGS). At the same time, HER2 protein expression was detected by immunohistochemistry(IHC), and then HER2 IHC 2+ specimens were further evaluated for their HER2 gene status by fluorescence in situ hybridization(FISH). The relationship between HER2 and/or FGFR variants and clinicopathological features of UC patients was analyzed.

Results: Among 133 UC cases, 50 FGFR gene variants were detected (37.6%). The types of variants were complex and varied, including mutations, fusions, coexistence of two mutations, coexistence of mutations and fusions, and coexistence with variants in other FGFR family genes. The most common was the FGFR3 variant, which accounted for 27.8% (37/133) of the overall population, including 31 FGFR3 mutations, 2 FGFR3 mutation/FGFR3 fusion coexistences, 2 FGFR2/FGFR3 co-mutations and 2 FGFR3/FGFR4 co-mutations. Four FGFR2 mutations (3.0%, 4/133), one FGFR4 mutation (1/133) and one FGFR2/FGFR4 co-mutation were found. FGFR double mutations coexisted in 20.0% (10/50) of this cohort. No FGFR1 mutations were detected. The eight mutations (G548R, G370C, M528I, R30C, A790T, S371C, S22L, and K650T) and four fusions (CASP7::FGFR2, FGFR2::BICD2, FBLN2::FGFR2, and FGFR3::GRSF1) we detected were not in the FGFR targeting drug Erdafitinib concomitant diagnostic coverage.FGFR variants coexisted with HER2 overexpression (IHC 2+ or 3+) in a total of 31 cases (62.0%, 31/50).

FGFR variants were negatively correlated with tumor grade, degree of infiltration, and Ki-67 index. HER2 expression level was correlated with tumor site and positively correlated with tumor grade and Ki-67 index. Dual abnormalities of FGFR and HER2 were negatively correlated with tumor grade, degree of infiltration, and Ki-67 index.

Conclusion: FGFR2/3/4 gene variants are present in UC; FGFR-positive UC is highly enriched for HER2 overexpression. Dual inhibition of FGFR and HER2 may be a candidate strategy for effective treatment of UC. It is necessary to expand the sample size to validate the present findings and conduct relevant clinical studies.